CMP Journal 2025-04-26
Statistics
Physical Review Letters: 14
Physical Review X: 2
arXiv: 62
Physical Review Letters
Essay: A Path for the Construction of a Muon Collider
Essay | Beam cooling | 2025-04-25 06:00 EDT
Diktys Stratakis
In this forward-looking PRL Essay, Diktys Stratakis outlines the essential steps, investigations, and R&D efforts needed to bring a Muon Collider to life. This collider, which could achieve TeV energies while maintaining precision, has the potential to significantly enrich our understanding of the Universe.
Phys. Rev. Lett. 134, 160001 (2025)
Beam cooling, Muon accelerators & neutrino factories, Storage rings, Lepton colliders
SENSEI at SNOLAB: Single-Electron Event Rate and Implications for Dark Matter
Research article | Dark matter | 2025-04-25 06:00 EDT
Itay M. Bloch et al. (SENSEI Collaboration)
We present results from data acquired by the SENSEI experiment at SNOLAB after a major upgrade in May 2023, which includes deploying 16 new sensors and replacing the copper trays that house the CCDs with a new light-tight design. We observe a single-electron event rate of $(1.39\pm{}0.11)\times{}{10}^{- 5}\text{ }\text{ }{\mathrm{e}}^{- }/\mathrm{pix}/\mathrm{day}$, corresponding to $(39.8\pm{}3.1)\text{ }\text{ }{\mathrm{e}}^{- }/\mathrm{gram}/\mathrm{day}$. This is an order-of-magnitude improvement compared to the previous lowest single-electron rate in a silicon detector and the lowest for any photon detector in the wavelength range between near-infrared and ultraviolet. We use these data to obtain a 90% confidence level upper bound of $1.53\times{}{10}^{- 5}\text{ }\text{ }{\mathrm{e}}^{- }/\mathrm{pix}/\mathrm{day}$ and to set constraints on sub-GeV dark matter candidates that produce single-electron events. We hypothesize that the data taken at SNOLAB in the previous run, with an older tray design for the sensors, contained a larger rate of single-electron events due to light leaks. We test this hypothesis using data from the SENSEI detector located in the MINOS cavern at Fermilab.
Phys. Rev. Lett. 134, 161002 (2025)
Dark matter, Dark matter direct detection, Particle dark matter, Solid-state detectors, Particle detectors
Search for Solar Boosted Dark Matter Particles at the PandaX-4T Experiment
Research article | Dark matter | 2025-04-25 06:00 EDT
Guofang Shen et al. (PandaX Collaboration)
We present a novel constraint on light dark matter utilizing 1.54 metric ton/year of data acquired from the PandaX-4T dual-phase xenon time projection chamber. This constraint is derived through detecting electronic recoil signals resulting from the interaction with solar-enhanced dark matter flux. Low-mass dark matter particles, lighter than a few $\mathrm{MeV}/{c}^{2}$, can scatter with the thermal electrons in the Sun. Consequently, with higher kinetic energy, the boosted dark matter component becomes detectable via contact scattering with xenon electrons, resulting in a few keV energy deposition that exceeds the threshold of PandaX-4T. We calculate the expected recoil energy in PandaX-4T considering the Sun’s acceleration with heavy mediators and the detection capabilities of the xenon detector. The first experimental search results using the xenon detector yield the most stringent upper limits cross section of $3.51\times{}{10}^{- 39}\text{ }\text{ }{\mathrm{cm}}^{2}$ at $0.08\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ for a solar boosted dark matter mass ranging from 0.02 to $10\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, achieving a 23-fold improvement compared with earlier experimental studies.
Phys. Rev. Lett. 134, 161003 (2025)
Dark matter, Dark matter direct detection, Particle dark matter, Dark matter detectors
Search for Light Dark Matter in Low-Energy Ionization Signals from XENONnT
Research article | Axions | 2025-04-25 06:00 EDT
E. Aprile et al. (XENON Collaboration)
*et al.*The first blinded search by the XENON-nT Collaboration using low-energy ionization signals places new constraints on hypothetical sub-keV dark matter.
Phys. Rev. Lett. 134, 161004 (2025)
Axions, Dark matter direct detection, Particle interactions, Weakly interacting massive particles
First Double-Differential Cross Section Measurement of Neutral-Current ${\pi }^{0}$ Production in Neutrino-Argon Scattering in the MicroBooNE Detector
Research article | Neutrinos | 2025-04-25 06:00 EDT
P. Abratenko et al. (MicroBooNE Collaboration)
We report the first double-differential cross section measurement of neutral-current neutral pion ($\mathrm{NC}{\pi }^{0}$) production in neutrino-argon scattering, as well as single-differential measurements of the same channel in terms of final states with and without protons. The kinematic variables of interest for these measurements are the ${\pi }^{0}$ momentum and the ${\pi }^{0}$ scattering angle with respect to the neutrino beam. A total of 4971 candidate $\mathrm{NC}{\pi }^{0}$ events fully contained within the MicroBooNE detector are selected using data collected at a mean neutrino energy of $\sim 0.8\text{ }\text{ }\mathrm{GeV}$ from $6.4\times{}{10}^{20}$ protons on target from the Booster Neutrino Beam at the Fermi National Accelerator Laboratory. After extensive data-driven model validation to ensure unbiased unfolding, the Wiener-singular-value-decomposition method is used to extract nominal flux-averaged cross sections. The results are compared to predictions from commonly used neutrino event generators, which tend to overpredict the measured $\mathrm{NC}{\pi }^{0}$ cross section, especially in the $0.2–0.5\text{ }\text{ }\mathrm{GeV}/\mathrm{c}$ ${\pi }^{0}$ momentum range and at forward scattering angles. Events with at least one proton present in the final state are also underestimated. This data will help improve the modeling of $\mathrm{NC}{\pi }^{0}$ production, which represents a major background in measurements of charge-parity violation in the neutrino sector and in searches for new physics beyond the standard model.
Phys. Rev. Lett. 134, 161802 (2025)
Neutrinos
Ab Initio Study of the Beryllium Isotopes $^{7}\mathrm{Be}$ to $^{12}\mathrm{Be}$
Research article | Binding energy & masses | 2025-04-25 06:00 EDT
Shihang Shen, Serdar Elhatisari, Dean Lee, Ulf-G. Meißner, and Zhengxue Ren
We present a systematic ab initio study of the low-lying states in beryllium isotopes from $^{7}\mathrm{Be}$ to $^{12}\mathrm{Be}$ using nuclear lattice effective field theory with the ${\mathrm{N}}^{3}\mathrm{LO}$ interaction. Our calculations achieve good agreement with experimental data for energies, radii, and electromagnetic properties. We introduce a novel, model-independent method to quantify nuclear shapes, uncovering a distinct pattern in the interplay between positive and negative parity states across the isotopic chain. By combining Monte Carlo sampling of the many-body density operator with a novel nucleon-grouping algorithm, the prominent two-center cluster structures, the emergence of one-neutron halo, complex nuclear molecular dynamics such as $\pi $ orbital and $\sigma $ orbital, emerge naturally.
Phys. Rev. Lett. 134, 162503 (2025)
Binding energy & masses, Nuclear many-body theory, Nuclear radii, Nuclear shapes and moments, Nuclear structure & decays, Nucleon distribution
Probing Exotic Cross-Shell Interactions at $N=28$ with Single-Neutron Transfer on $^{47}\mathrm{K}$
Research article | Nuclear structure & decays | 2025-04-25 06:00 EDT
C. J. Paxman et al.
We present the first measurement of the $^{47}\mathrm{K}(d,p\gamma )^{48}\mathrm{K}$ transfer reaction, performed in inverse kinematics using a reaccelerated beam of $^{47}\mathrm{K}$. The level scheme of $^{48}\mathrm{K}$ has been greatly extended, with nine new bound excited states identified and spectroscopic factors deduced. Uniquely, the $^{47}\mathrm{K}(d,p)$ reaction gives access to nuclear states that are sensitive to the interaction of protons and neutrons in the widely spaced $1s$ and $fp$ orbitals, respectively. Detailed comparisons with SDPF-U and SDPF-MU shell-model calculations reveal a number of discrepancies between theory and experiment. Intriguingly, a systematic overestimation of spectroscopic factors and a poor reproduction of the energies for ${1}^{- }$ states suggests that the mixing between the $\pi {s}{1/2}^{1}{d}{3/2}^{4}$ and $\pi {s}{1/2}^{2}{d}{3/2}^{3}$ proton configurations in $^{48}\mathrm{K}$ is not correctly described using current interactions, challenging our description of light nuclei around the $N=28$ island of inversion.
Phys. Rev. Lett. 134, 162504 (2025)
Nuclear structure & decays, Shell model, 39 ≤ A ≤ 58, Optical, coupled-channel & distorted wave models, Radiation detectors, Radioactive beams
Photoelectron Spin Texture in Tunneling Ionization Induced by a Linearly Polarized Laser Pulse
Research article | Atomic & molecular processes in external fields | 2025-04-25 06:00 EDT
Pei-Lun He, Zhao-Han Zhang, Karen Z. Hatsagortsyan, and Christoph H. Keitel
The spin polarization of photoelectrons in tunneling ionization is investigated using numerical solutions of the time-dependent Schr"odinger equation in companion with our analytic treatment via the spin-resolved strong-field approximation and classical trajectory Monte Carlo simulations. We demonstrate a nontrivial spin texture of photoelectrons in momentum space, exhibiting a vortex structure relative to the laser polarization axis. The momentum-resolved polarization stems from the emergence of spin-correlated quantum orbits in the continuum. For direct electrons in few-cycle pulses, the nonvanishing initial transverse velocity of the electron is responsible for the polarization, while in long pulses, the spin texture is essentially shaped by recollisions. Furthermore, the interference between direct and rescattering ionization leads to spin-polarized electron holography, offering an alternative method to extract atomic fine structural information.
Phys. Rev. Lett. 134, 163201 (2025)
Atomic & molecular processes in external fields, Multiphoton or tunneling ionization & excitation, Strong field ionization & excitation
Corrugation-Dominated Mechanical Softening of Defect-Engineered Graphene
Research article | Graphene | 2025-04-25 06:00 EDT
Wael Joudi, Rika Saskia Windisch, Alberto Trentino, Diana Propst, Jacob Madsen, Toma Susi, Clemens Mangler, Kimmo Mustonen, Florian Libisch, and Jani Kotakoski
Microscopy and molecular dynamics suggest that the decrease in the two-dimensional elastic modulus of graphene with engineered defects is primarily due to corrugations from local strain at vacancies with two or more missing atoms, while single vacancies have a negligible effect.
Phys. Rev. Lett. 134, 166102 (2025)
Graphene, Atomic force microscopy, Convolutional neural networks, Machine learning models, Mechanical testing, Molecular dynamics, Scanning transmission electron microscopy
Sensing Quantum Vacuum Fluctuations with Non-Gaussian Electronic Noise
Research article | Non-gaussian quantum states | 2025-04-25 06:00 EDT
Clovis Farley, Edouard Pinsolle, and Bertrand Reulet
The statistics of electron transport in a quantum conductor is affected by fluctuations of its voltage bias. Here, we show experimentally how a third order correlation in the electromagnetic field arises from the noise of a tunnel junction in the microwave domain being modulated by the vacuum fluctuations generated by a resistor at ultralow temperature. This provides a way to measure the vacuum fluctuations experienced by the junction, not offset by the unavoidable noise added by the detection setup.
Phys. Rev. Lett. 134, 166301 (2025)
Non-gaussian quantum states, Quantum fluctuations & noise, Shot noise, Tunnel junctions, Noise measurements
Moir'e Kramers-Weyl Fermions with Ideal Radial Spin Texture from Structural Chirality
Research article | Electronic structure | 2025-04-25 06:00 EDT
D. J. P. de Sousa, Seungjun Lee, and Tony Low
We demonstrate that two-dimensional Kramers-Weyl fermions can be engineered in spin-orbit coupled twisted bilayers, where the chiral structure of these moir'e systems breaks all mirror symmetries, confining Kramers-Weyl fermions to high-symmetry points in the Brillouin zone under time reversal symmetry. Our theoretical analysis reveals a symmetry-enforced, Weyl-like spinful interlayer moir'e coupling that universally ensures an ideal radial spin-texture at arbitrary twist angles, under ${C}{nz}$ symmetry with $n>2$. First principles density functional calculation confirm the realization of these fermions in twisted $\alpha \text{- }{\mathrm{In}}{2}{\mathrm{Se}}_{3}$ homobilayers, where flat bands and out-of-plane ferroelectric polarization in each layer guarantee two-dimensional Kramers-Weyl physics with ideal radial spin textures.
Phys. Rev. Lett. 134, 166401 (2025)
Electronic structure, First-principles calculations, Flat bands, Spin-orbit coupling, Topological materials, Twistronics
Quadrupolar and Dipolar Excitons in Bilayer $2H\text{- }{\mathrm{MoSe}}_{2}$
Research article | Excitons | 2025-04-25 06:00 EDT
Shun Feng, Aidan J. Campbell, Bibi Mary Francis, Hyeonjun Baek, Takashi Taniguchi, Kenji Watanabe, Iann C. Gerber, Brian D. Gerardot, and Mauro Brotons-Gisbert
Quadrupolar exciton states are shown experimentally to be present in the reflectance contrast spectrum of 2H-stacked bilayer MoSe2.
Phys. Rev. Lett. 134, 166901 (2025)
Excitons, Magneto-optics, Optoelectronics, Photonics, Spintronics, Valleytronics, Layered semiconductors, Transition metal dichalcogenides, Density functional theory, GW method, Surface differential reflectance spectroscopy
Waveform Proportionality and Taylor’s Law Induced by Synchronization of Periodic and Chaotic Oscillators
Research article | Chaos | 2025-04-25 06:00 EDT
Yuzuru Mitsui and Hiroshi Kori
Taylor’s law (TL), the scaling relationship between mean and variance, has been observed in various fields. However, the underlying reasons for the widespread occurrence of TL, the frequent appearance of the TL exponent value close to 2, and the relationship between temporal and spatial TLs are not fully understood. Here, using coupled oscillator models, we analytically and numerically demonstrate that synchronization can induce TL. In particular, we show that strong synchronization leads to waveform proportionality, resulting in temporal and spatial TLs with an exponent 2. Our results can help infer the existence of synchronization solely from the correlation between mean and variance.
Phys. Rev. Lett. 134, 167202 (2025)
Chaos, Complex systems, Coupled oscillators, Population dynamics, Scaling laws of complex systems, Synchronization, Chaotic systems, Dynamical systems
Differential Elasticity Affects Lineage Segregation of Embryonic Stem Cells
Research article | Cell mechanics | 2025-04-25 06:00 EDT
Christine M. Ritter, Tianxiang Ma, Natascha Leijnse, Younes Farhangi Barooji, William Hamilton, Joshua M. Brickman, Amin Doostmohammadi, and Lene B. Oddershede
The segregation of two cell types at the earliest stages of embryo development may be enabled by differences in their stiffness.
Phys. Rev. Lett. 134, 168401 (2025)
Cell mechanics, Developmental biology, Developmental pattern formation, Emergence of patterns, Morphogenesis, Stem cells, Tissues
Physical Review X
Robust Nodal Behavior in the Thermal Conductivity of Superconducting ${\mathrm{UTe}}_{2}$
Research article | Spin-triplet pairing | 2025-04-25 06:00 EDT
Ian M. Hayes, Tristin E. Metz, Corey E. Frank, Shanta R. Saha, Nicholas P. Butch, Vivek Mishra, P. J. Hirschfeld, and Johnpierre Paglione
Ultralow-temperature thermal conductivity measurements reveal a point node superconducting gap structure in UTe2. The findings confirm robust spin-triplet superconductivity and advance the search for topological superconductors.
Phys. Rev. X 15, 021029 (2025)
Spin-triplet pairing, Superconducting gap, Superconductivity
Theory of Electron-Phonon Interactions in Extended Correlated Systems Probed by Resonant Inelastic X-Ray Scattering
Research article | Electron-phonon coupling | 2025-04-25 06:00 EDT
Jinu Thomas, Debshikha Banerjee, Alberto Nocera, and Steven Johnston
A new framework reveals how lattice vibrations contribute to resonant inelastic x-ray scattering experiments, offering clearer insight into quantum materials.
Phys. Rev. X 15, 021030 (2025)
Electron-phonon coupling, 1-dimensional spin chains, Density matrix renormalization group, Hubbard model, Resonant inelastic x-ray scattering, X-ray absorption spectroscopy
arXiv
Some Peculiarities of Dielectric Spectroscopy in Ferroelectric Nematics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
Yuri P. Panarin, Neelam Yadav, Rahul Uttam, Wanhe Jiang, Georg H. Mehl, Jagdish K. Vij
Dielectric spectroscopy is known as one of the most powerful techniques for studying ferroelectric and other polar materials. Since the discovery of ferroelectricity in Liquid Crystals, it has been successfully employed for the characterization of ferro-, antiferro- and ferri-electric liquid crystalline phases. However, recently the Boulder group raised the question of the applicability of dielectric spectroscopy for characterizing ferroelectric nematics due to parasitic effects from the insulating alignment layers. This affects the apparent/measured values of the dielectric permittivity. In this paper, we study this effect in greater detail. The following issues will receive special attention: Are the real values of dielectric permittivity lower or higher than the measured ones? Can the real values of dielectric permittivity be recovered in the cell with alignment layers? We also provide an example of the effect of insulating alignment layers in a non-ferroelectric nematic phase.
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft)
16 pages, 6 Figures
Indirect Tunneling Enabled Spontaneous Time-Reversal Symmetry Breaking and Josephson Diode Effect in TiN/Al$2$O$3$/Hf${0.8}$Zr${0.2}$O$_2$/Nb tunnel junctions
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-25 20:00 EDT
Shaoqing Ding, Jinyuan Yao, Zhen Bi, Quyen Tran, Bangzhi Liu, Qi Li, Susan Trolier-McKinstry, Thomas N. Jackson, Ying Liu
Josephson diode (JD) effect found in Josephson tunnel junctions (JTJs) has attracted a great deal of attention due to its importance for developing superconducting circuitry based quantum technologies. So far, the highly desirable electrical control of the JD effect has not been demonstrated in any JTJ prepared by techniques used in semiconductor industry. We report the fabrication of JTJs featuring a composite tunnel barrier of Al$ _2$ O$ _3$ and Hf$ _{\mathrm{0.8}}$ Zr$ _\mathrm{0.2}$ O$ _2$ prepared by complementary-metal-oxide-semiconductor (CMOS) compatible atomic layer deposition (ALD). These JTJs were found to show the JD effect in nominally zero magnetic fields with the nonreciprocity controllable using an electric training current, yielding a surprisingly large diode efficiency not achieved previously. The quasiparticle tunneling, through which the Josephson coupling in a JTJ is established, was found to show no nonreciprocity. We attribute these observations to the simultaneous presence of positive and negative Josephson couplings, with the latter originating from indirect tunneling. The resulted spontaneous time-reversal symmetry breaking and the double-minima washboard potential for the ensemble averaged phase difference in the resistively and capacitively shunted junction (RCSJ) model are shown to fully account for the experimentally observed JD effect.
Superconductivity (cond-mat.supr-con)
Fluxoid Valve Effect in Full-Shell Nanowire Josephson Junctions
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-25 20:00 EDT
Carlos Payá, F.J. Matute-Cañadas, A. Levy Yeyati, Ramón Aguado, Pablo San-Jose, Elsa Prada
We introduce a new type of supercurrent valve based on full-shell nanowires. These hybrid wires consist of a semiconductor core fully wrapped in a thin superconductor shell and subjected to an axial magnetic field. Due to the tubular shape of the shell, the superconductor phase acquires an integer number $ n$ of $ 2\pi$ twists or fluxoids that increases in steps with applied flux. By connecting two such hybrid wires, forming a Josephson junction (JJ), a flux-modulated supercurrent develops. If the two superconducting sections of the JJ have different radii $ R_1$ and $ R_2$ , they can develop equal or different fluxoid numbers $ n_1,n_2$ depending on the field. If $ n_1\neq n_2$ the supercurrent is blocked, while it remains finite for $ n_1=n_2$ . This gives rise to a fluxoid valve effect controlled by the applied magnetic field. We define a fluxoid-valve quality factor that is perfect for cylindrically symmetric systems and decreases as this symmetry is reduced. We further discuss the role of Majorana zero modes at the junction when the full shell-nanowires are in topological superconducting regime.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 4 figures
Bosonic vs. Fermionic Matter in Quantum Simulations of $2+1$D Gauge Theories
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-25 20:00 EDT
N. S. Srivatsa, Jesse J. Osborne, Debasish Banerjee, Jad C. Halimeh
Quantum link models extend lattice gauge theories beyond the traditional Wilson formulation and present promising candidates for both digital and analog quantum simulations. Fermionic matter coupled to $ U(1)$ quantum link gauge fields has been extensively studied, revealing a phase diagram that includes transitions from the columnar phase in the quantum dimer model to the resonating valence bond phase in the quantum link model, potentially passing through a disordered liquid-like phase. In this study, we investigate the model coupled to hardcore bosons and identify a similar phase structure, though with a more intricate mixture of phases around the transition. Our analysis reveals that near the transition region, a narrow and distinct ordered phase emerges, characterized by gauge fields forming plaquette configurations with alternating orientations, which is then followed by a thinner, liquid-like regime. This complexity primarily stems from the differences in particle statistics, which manifest prominently when the matter degrees of freedom become dynamic. Notably, our findings suggest that bosons can effectively replace fermions in lattice gauge theory simulations, offering solutions to the challenges posed by fermions in both digital and analog quantum simulations.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Gases (cond-mat.quant-gas), High Energy Physics - Lattice (hep-lat), Quantum Physics (quant-ph)
5+2 pages, 4+3 figures
2D Anderson Localization and KPZ sub-Universality Classes : sensitivity to boundary conditions and insensitivity to symmetry classes
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-04-25 20:00 EDT
Nyayabanta Swain, Shaffique Adam, Gabriel Lemarié
We challenge two foundational principles of localization physics by analyzing conductance fluctuations in two dimensions with unprecedented precision: (i) the Thouless criterion, which defines localization as insensitivity to boundary conditions, and (ii) that symmetry determines the universality class of Anderson localization. We reveal that the fluctuations of the conductance logarithm fall into distinct sub-universality classes inherited from Kardar-Parisi-Zhang (KPZ) physics, dictated by the lead configurations of the scattering system and unaffected by the presence of a magnetic field. Distinguishing between these probability distributions poses a significant challenge due to their striking similarity, requiring sampling beyond the usual threshold of $ \sim 10^{-6}$ accessible through independent disorder realizations. To overcome this, we implement an importance sampling scheme - a Monte Carlo approach in disorder space - that enables us to probe rare disorder configurations and sample probability distribution tails down to $ 10^{-30}$ . This unprecedented precision allows us to unambiguously differentiate between KPZ sub-universality classes of conductance fluctuations for different lead configurations, while demonstrating the insensitivity to magnetic fields.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
15 pages, 16 figures
Laughlin-like states of few atomic excitations in small subwavelength atom arrays
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-25 20:00 EDT
Błażej Jaworowski, Darrick E. Chang
Atom arrays with sub-wavelength lattice constant can exhibit fascinating optical properties. Up to now, much of our understanding of these systems focuses on the single-excitation regime. In one relevant example, the combination of multiple excited states and magnetic fields can yield topological band structures, albeit with dispersion relations that can exhibit divergences near the light cone. Here, we go beyond the single-excitation level to show that such systems can give rise to few-particle Laughlin-like states. In particular, we consider small honeycomb ``flakes,’’ where the divergences can be smeared out by finite-size effects. By choosing an appropriate value of magnetic field we thereby obtain an energy spectrum and eigenstates resembling those of Landau levels. The native hard-core nature of atomic excitations then gives rise to multi-excitation Laughlin-like states. This phenomenon occurs not only in samples of tens of sites, but also in a minimal nanoring system of only six sites. Next, considering two-particle Laughlin-like states, we show that they can be driven by uniform light, and that correlations of the output light contain identifying fingerprints of these states. We believe that these results are a step towards new paradigms of engineering and understanding strongly-correlated many-body states in atom-light interfaces.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Optics (physics.optics)
19 pages, 18 figures
Density Functional Theory ToolKit (DFTTK) to Automate First-Principles Thermodynamics via the Quasiharmonic Approximation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
Nigel Lee En Hew, Luke Allen Myers, Axel van de Walle, Shun-Li Shang, Zi-Kui Liu
The Helmholtz energy is a key thermodynamic quantity representing available energy to do work at a constant temperature and volume. Despite a well-established methodology from first-principles calculations, a comprehensive tool and database are still lacking. To address this gap, we developed an open-source Density Functional Theory Tool Kit (DFTTK), which automates first-principles thermodynamics using the quasiharmonic approximation (QHA) for Helmholtz energy predictions. This Python-based package provides a solution for automating the calculation and analysis of various contributions to Helmholtz energy, including the static total energy contributions at 0 K in terms of DFT-based energy-volume curves, vibrational contributions from the Debye-Gruneisen model and phonons, and thermal electronic contributions via the electronic density of states. The QHA is also implemented to calculate the Gibbs energy and associated properties at constant temperature and pressure. The present work demonstrates DFTTK’s capabilities through case studies on a simple FCC Al and various collinear magnetic configurations of Invar Fe3Pt, where DFTTK enumerates all unique configurations and their associated multiplicities. DFTTK is freely available on GitHub, and its modular design allows for the easy addition of new workflows.
Materials Science (cond-mat.mtrl-sci)
Type-II Weyl nodes, flat bands, and evidence for a topological Hall-effect in the new ferromagnet FeCr$_3$Te$_6$
New Submission | Other Condensed Matter (cond-mat.other) | 2025-04-25 20:00 EDT
Shyam Raj Karullithodi, Vadym Kulichenko, Mario A. Plata, Andrzej Ptok, Sang-Eon Lee, Gregory T. McCandless, Julia Y. Chan, Luis Balicas
The interplay between linearly dispersing or Dirac-like, and flat electronic bands, for instance, in the kagome ferromagnets, has attracted attention due to a possible interplay between topology and electronic correlations. Here, we report the synthesis, structural, electrical, and magnetic properties of a single-crystalline ferromagnetic compound, namely Fe$ _{1/3}$ CrTe$ _2$ or FeCr$ _3$ Te$ 6$ , which crystallizes in the $ P\bar{3}m1$ space group instead of the $ I2/m$ previously reported for FeCr$ 2$ Te$ 4$ . Electronic band structure calculations reveal type-II Dirac nodes and relatively flat bands near the Fermi level ($ \varepsilon_F$ ). This compound shows onset Curie temperature $ T{\text{c}}\simeq 120$ K, followed by an additional ferromagnetic transition near $ T{\text{c2}} \sim 92.5 $ K. Below $ T{\text{c}}$ , FeCr$ _3$ Te$ _6$ displays a pronounced anomalous Hall effect, as well as sizable coercive fields that exceed $ \mu_0H = 1$ ~T at low $ T$ s. However, a scaling analysis indicates that the anomalous Hall effect results from a significant intrinsic contribution, as expected from the calculations, but also from the extrinsic mechanism, i.e., scattering. The extrinsic contribution probably results from occupational disorder at the 1b Fe-site within the van der Waals gap of the CrTe$ _2$ host. We also observe evidence for a topological Hall component superimposed onto the overall Hall response, suggesting the presence of chiral spin textures akin to skyrmions in this centrosymmetric system. Their possible presence will require experimental confirmation.
Other Condensed Matter (cond-mat.other)
8 pages, 7 figures
Physical Review Materials, 2025
Effects of chemical disorder and spin-orbit coupling on electronic-structure and Fermi-surface topology of YbSb-based monopnictides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
Maxwell Eibert, Christopher Burgio, Tyler Del Rose, Prince Sharma, Yaroslav Mudryk, Prashant Singh
In this work, we study the influence of disorder on the electronic structure of YbSb – a rare-earth monopnictide featuring a simple rock-salt (B1) crystal structure and a well-defined Fermi surface topology – by employing first-principles density functional theory (DFT). We focus on chemical disorder introduced through Te and Al doping, selected based on their thermodynamic stability in alloyed configurations, to understand how such perturbations modify the electronic states of YbSb. Our results indicate that Te doping predominantly introduces electron-like states at the \textit{X} and \textit{L} points, while Al doping leads to a suppression of hole-like states at $ \Gamma$ , effectively driving the system from a semimetallic state to one characterized by very narrow-gap behavior at $ \Gamma$ . This modulation of the Fermi surface, particularly the reduction of central hole pockets at $ \Gamma$ , plays a central role in altering inter-pocket scattering – a mechanism critical for tuning quantum transport properties, including superconductivity. This disorder-driven modulation of the Fermi surface, particularly the suppression of central hole pockets at $ \Gamma$ , controls inter-pocket scattering, which is essential for optimizing quantum transport properties, including superconductivity. Our results show that disorder can be effectively used as a means of engineering band topology, thereby tuning quantum-related responses through tailored electronic structure.
Materials Science (cond-mat.mtrl-sci)
18 pages, 8 figures, 79 references
Magneto-Optical Analysis of Magnetic Anisotropy in Ultrathin Tm${3}$Fe${5}$O$_{12}$/Pt Bilayers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
T. Nathan Nunley, Daniel Russell, Liang-Juan Chang, David Lujan, Jeongheon Choe, Side Guo, Shang-Fan Lee, Fengyuan Yang, Xiaoqin Li
Magnetic bilayers consisting of an epitaxially grown ferrimagnetic insulator and a heavy metal layer are attractive for spintronic application because of the opportunity for electric control and read-out of spin textures via spin orbit torque. Here, we investigate ultrathin thulium iron garnet (TmIG)/Pt bilayers when the TmIG layer thickness is 3 nm and below using a sensitive Sagnac magneto-optical Kerr effect technique. We compare the hysteresis loops from out-of-plane and in-plane applied magnetic fields. The preferred magnetization orientation evolves with the TmIG thickness and the presence of the Pt overlayer. We quantify the evolution of the magnetic anisotropy in these ultrathin films and find a significant change even when the TmIG thickness is varied by less than 1 nm. In these ultrathin films, the presence of a Pt overlayer changes the effective anisotropy field by more than a factor of 2, suggesting that the interfacial anisotropy at the Pt/TmIG interface plays a critical role in this regime.
Materials Science (cond-mat.mtrl-sci)
8 pages, 4 figures, 2 tables, submitted for review
Lattice Dynamics of Energy Materials Investigated by Neutron Scattering
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
In this thesis, I discuss several basic science studies in the field of energy materials using neutron scattering as a probe for the lattice dynamics. To enable understanding of neutron scattering spectra, I also use computational and theoretical methods. These methods and neutron scattering in general are discussed in detail in Chapter 2. It is assumed that the reader is familiar with basic quantum mechanics as well as with solid state physics topics including the band theory of electrons, harmonic lattice dynamics, and molecular dynamics. For the unfamiliar reader, the details of electronic structure theory and lattice dynamics that are needed to understand the methods in Chapter 2 are provided in Chapters 3 and 4. In the remaining chapters, these methods are applied to the study of several energy materials: cuprate La2CuO4,(hybrid) solar perovskite CH3NH3PbI3, and thermoelectric clathrate Ba8Ga16Ge30.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), Computational Physics (physics.comp-ph)
This is my doctoral dissertation; it contains original content in a few places, so I am publishing on arxiv to make available
Semimetals without correspondence between the topological charge of nodal line/surface and Fermi arc
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
Xue-Min Yang, Jiang-Shan Chen, Ying Chen, Yu-Hang Qin, Hong Wu
It is generally believed that there is a correspondence between the topological charge of nodal points or lines and the presence of Fermi arcs. Using a $ \mathcal{P}\mathcal{T}$ -invariant system as an example, we demonstrate that this general belief is no longer valid. When two charged nodal lines or surfaces touch, the topological charge {dissipates without gap opening}, yet the surfaces or hinge Fermi arcs can remain preserved. It is found that both static and Floquet semimetals can exhibit Fermi arcs, even when the nodal lines or surfaces do not carry a $ Z_2$ charge from second Stiefel-Whitney class.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Ordered and Disordered Skyrmion States on a Square Substrate
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
J. C. Bellizotti Souza, C. J. O. Reichhardt, C. Reichhardt, N. P. Vizarim, P. A. Venegas
We examine the ordering of skyrmions interacting with a square substrate created from a modulation of anisotropy using atomistic simulations. We consider fillings of {\it f} = 1.5, 2.0, 2.5, 3.0, and 3.5 skyrmions per potential minimum as a function of magnetic field and sample size. For a filling of {\it f} = 2.0, we find various dimer orderings, such as tilted dimer states, as well as antiferromagnetic ordering that is similar to the colloidal dimer ordering seen on square substrates. The ability of the skyrmions to change shape or annihilate produces additional states that do not occur in the colloidal systems. For certain parameters at {\it f} = 2.0, half of the skyrmions can annihilate to form a square lattice, or a superlattice of trimers and monomers containing skyrmions of different sizes can form. At lower fields, ordered stretched skyrmion states can appear, and for zero field, there can be ordered stripe states. For {\it f} = 3.0, we find ferromagnetic ordered trimers, tilted lattices, columnar lattices, and stretched phases. For fillings of {\it f} = 1.5 and 2.5, we find bipartite lattices, different ordered and disordered states, and several extended disordered regions produced by frustration effects.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
15 pages, 14 figures
Inference of phase field fracture models
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
Elizabeth Livingston, Siddhartha Srivastava, Jamie Holber, Hashem M. Mourad, Krishna Garikipati
The phase field approach to modeling fracture uses a diffuse damage field to represent a crack. This addresses the singularities that arise at the crack tip in computations with sharp interface models, mollifying some of the difficulties associated with the mathematical and numerical treatment of fracture. The introduction of the diffuse field helps with crack propagation dynamics, enabling phase-field approaches to model all phases of damage from crack initiation to propagation, branching, and merging. Specific formulations, beginning with brittle fracture, have also been shown to converge to classical solutions. Extensions to cover the range of material failure, including ductile and cohesive fracture, leads to an array of possible models. There exists a large body of studies of these models and their consequences for crack evolution. However, there have not been systematic studies into how optimal models may be chosen. Here we take a first step in this direction by developing formal methods for identification of the best parsimonious model of phase field fracture given full-field data on the damage and deformation fields. We consider some of the main models that have been used to model damage, its degradation of elastic response, and its propagation. Our approach builds upon Variational System Identification (VSI), a weak form variant of the Sparse Identification of Nonlinear Dynamics (SINDy). In this first communication we focus on synthetically generated data but we also consider central issues associated with the use of experimental full-field data, such as data sparsity and noise.
Materials Science (cond-mat.mtrl-sci)
36 pages, 12 figures
Weyl nodes and Kondo interaction in noncentrosymmetric semimetals RGaGe (R=La, Ce and Pr) with long Fermi arcs
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-25 20:00 EDT
In non-centrosymmetric Weyl semimetals based on rare-earth compounds, the correlation effects among $ f$ electrons may play a crucial role in shaping the properties of Weyl nodes, potentially giving rise to magnetic Weyl semimetals or correlated Weyl excitations. Here, we investigates a recently identified class of magnetic rare-earth Weyl semimetals, RGaGe (R = La, Ce, and Pr). By employing a combination of density functional theory (DFT) and dynamical mean-field theory (DMFT) calculations, we demonstrate that under ambient pressure, the $ f$ electrons in CeGaGe and PrGaGe are nearly fully localized. Concurrently, three inequivalent types of Weyl nodes emerge near the Fermi level due to intersections between $ spd$ bands. Notably, one type of Weyl point exhibits substantial chiral separation (significantly greater than in CeAlSi and CeAlGe), leading to the formation of long and well-defined surface Fermi arcs on the (001) surface. These Fermi arcs remain well-separated by bulk states, thereby facilitating future experimental observations. In contrast, the chiral separation of Weyl points in LaGaGe is relatively modest. Upon application of volume compression, the $ f$ electrons in CeGaGe progressively become itinerant and begin to obscure the Weyl nodes formed by $ spd$ electrons, rendering them less accessible for direct observation. These findings suggest that in correlated materials, particularly $ f$ -electron systems, even when $ f$ electrons do not directly contribute to the formation of topological nodes, they can still exert a profound influence on the characteristics of Weyl nodes.
Strongly Correlated Electrons (cond-mat.str-el)
8 pages, 7 figures
Hyperuniform Mixing of Binary Active Spinners
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-25 20:00 EDT
Rui Liu, Mingcheng Yang, Ke Chen
Spinner mixtures consisting of both clockwise and counterclockwise self-spinning particles are often expected to phase separate. However, we demonstrate that such a demixing is absent for dimer (or rod-like) spinners. These particles always mix, even in a globally-hyperuniform way, with the total structure factor $ S(q\to 0)\sim q^{\alpha},(\alpha>0)$ . This global hyperuniformity can be enhanced or weakened by changes in the driving torques or the particle density in various ways. The corresponding microscopic mechanism is attributed to the competition between a dynamical heterocoordination effect and effective like-particle attractions. Critical scaling for the absorbing state transition of the system is also found to persist, with a significant shift in its critical point observed. The system can be further thermalized, by the driving torques or through thermostating, into an ideal solution with identical partial radial distribution functions, which denys the possibility of being multi-hyperuniform. A simply-extented coupled density-oscillator theory explains why the system can not be multi-hyperuniform, but can have a global hyperuniformity with the scaling exponent $ \alpha$ approaching $ 2$ . Such a hyperuniform mixing provides a way to regulate the topological boundary flows of this chiral system, and this mixing regulation is found to barely affect the bulk density fluctuations and even preserve the localization of the flows and the bulk hyperuniformity.
Soft Condensed Matter (cond-mat.soft)
Quantum geometry and elliptic optical dichroism in $p$-wave magnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
The quantum geometric tensor is composed of the Berry curvature and the quantum metric, which is observable by means of optical absorption of elliptically polarized light. Especially, the quantum geometric tensor at the zero-momentum is observable by the optical absorption at the optical band edge. In this context, we study optical absorption of a $ p$ -wave magnet under irradiation of elliptically polarized light. The $ p$ -wave magnet has a band splitting along one axis, which we choose the $ x$ axis. We obtain analytic formulae for the optical conductivity up to the second order in the magnitude of the Néel vector. In particular, the optical conductivity is exactly obtained when the Néel is along the $ x$ , $ y$ and $ z$ axis. It shows strong ellipticity a dependence of the light polarization, which is an elliptic dichroism. Especially, there is a perfect elliptic optical dichroism when the Néel vector is along the $ y$ axis. It is possible to determine the Néel vector by measuring the ellipticity of the perfect elliptic dichroism.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
8 pages, 5 pages
Dual role of stripe phase on superconducting correlation in a bilayer square lattice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-25 20:00 EDT
Ting Guo, Lufeng Zhang, Tianxing Ma, Hai-Qing Lin
While the stripe phase has been observed not only in monolayer cuprates but also in bilayer cuprates, research on its behavior in bilayer cuprates has been limited. Using constrained path quantum Monte Carlo, we explore the effect of stripes on the bilayer square lattice. We find the system exhibits short-range antiferromagnetism, which is enhanced by stripes and is strongest when the electron density of the interstriped rows reaches half-filling. The hole doping concentration plays a crucial role in the interaction between stripes and superconductivity. The $ d$ -wave pairing is enhanced by stripe potential $ V_0$ at the hole doping $ \delta_h=1/4$ , whereas it is suppressed by stripe potential $ V_0$ at the hole doping $ \delta_h=1/8$ . We elucidate this phenomenon through an analysis of the magnetism of the interstriped rows. Furthermore, the effective $ d$ -wave pairing is stronger in the bilayer model compared to the monolayer model when stripes are introduced on the square lattice. Overall, our unbiased numerical simulations provide a further understanding of the crossed bilayer square lattice model.
Strongly Correlated Electrons (cond-mat.str-el)
8 pages and 7 figures
Magnetic-field oscillations of the critical temperature in ultraclean, two-dimensional Type-I superconductor
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-25 20:00 EDT
Aiying Zhao, Richard A Klemm, Qiang Gu
We investigate the influence of Landau Levels (LLs) and Zeeman energy, induced by an applied magnetic field $ {\bf B}$ , on the critical temperature $ T_c$ for two-dimensional (2D) ultraclean metals using a fully quantum mechanical approach within the Bardeen-Cooper-Schrieffer (BCS) theory. In contrast to standard BCS theory, it allows for Cooper pair formation between electrons with opposite spins and momenta along the $ {\bf B}$ direction, both on the same or on neighboring LLs. Our quantum mechanical treatment of LLs reveals that $ T_c({\bf B})$ for electrons paired on the same LLs exhibits oscillations around the BCS critical temperature at lower magnetic fields, a phenomenon analogous to the de Haas-van Alphen effect. The Zeeman energy leads to a decrease in $ T_c({\bf B})$ with increasing $ {\bf B}$ for electrons paired both on the same and on neighboring LLs. Notably, as the $ g$ -factor increases, the amplitude of the $ {\bf B}$ oscillations gradually diminishes until they vanish at higher magnetic fields. Conversely, for small $ g$ -factors, electron pairing on the same or on neighboring LLs can result in a re-entrant superconducting phase at very high magnetic fields.
Superconductivity (cond-mat.supr-con)
8 pages, 5 figures,
Anisotropy-induced collapse of Landau levels in Weyl semimetals and its detection via the planar Hall effect
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
Fu-Yang Chen, Zhuo-Hua Chen, Hou-Jian Duan, Mou Yang, Rui-Qiang Wang, Ming-Xun Deng
The planar Hall effect (PHE) is a powerful tool for characterizing Weyl semimetals (WSMs). Here, we inves- tigate the PHE in general anisotropic WSMs under strong magnetic fields. We analytically derive the Landau levels (LLs) and their wavefunctions using the Bogoliubov transformation, where the tilt vector, anisotropic axis of the Fermi velocity, and the magnetic field can be oriented in arbitrary directions. Notably, due to the interaction with the magnetic field and the anisotropy of the Fermi velocity, the component of the tilt vector perpendicular to the magnetic field can induce a tilt in the LLs parallel to the magnetic field. Our analytical re- sults show that the LLs do not collapse in type-I WSMs but must collapse in type-II WSMs when the magnetic field is vertical to the tilt vector. More importantly, we demonstrate that the magnetotransport signal of the LL collapse, which manifests as significant enhancement and quantum oscillations in the longitudinal and planar Hall conductivities simultaneously, can be used to identify the phase transition from type-I to type-II WSMs.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 5 figures
Broad-temperature-range ultrafast terahertz excitation of collective dynamics in polar skyrmions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
Wei Li, Sixu Wang, Pai Peng, Haojie Han, Xinbo Wang, Jing Ma, Jianlin Luo, Jun-Ming Liu, Jing-Feng Li, Ce-Wen Nan, Qian Li
Ultrafast coherent control of electric dipoles using strong terahertz (THz) pulses provides a means to discover hidden phases of materials and potentially leads to applications in high-speed electro-optic devices. The effectiveness of this means, albeit demonstrated in architype (incipient) ferroelectric systems such as SrTiO3, hinges on a spectral overlapping between their soft phonon modes within the excitation bandwidth of THz pulses. Generally this can only induce an appreciable coupling close to the phase transition temperatures, where the lattice phonons substantially soften. Because of their emergent subterahertz collective dynamics, a fundamentally distinct and effective THz coupling mechanism can be envisaged in topological polar structures recently discovered in PbTiO3/SrTiO3 superlattices. Here, we show that polar skyrmions can be coherently driven into a hidden phase with transient macroscopic polarization, as probed based on THz field-induced second harmonic generation and optical Kerr effects. Such an ultrafast THz-driven phase transition is found to sustain across a broad temperature range of 4-470 K, in accordance with the equilibrium stability field of the skyrmions. Supplemented by dynamical phase-field simulations, we identify the spatial symmetries and relaxation behaviors of the excited collective modes, thereby revealing their correlation with the emergence of the polar phases. Our results unveil the exotic dynamical properties of topological polar structures, which could be technologically exploited given their remarkable flexibility in structure design and tunability under external fields.
Materials Science (cond-mat.mtrl-sci)
24 pages manuscript and 18 pages supplementary materials
Synchronized in-gap edge states and robust copropagation in topological insulators without magnetic flux
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
Liangcai Xie, Tianyi He, Liang Jin
Copropagation of antichiral edge states in the metallic phase requires the bulk states as counterpropagating modes. Without the band gap protection, the copropagation along the boundaries is easily scattered into the bulk and the counterpropagation in the bulk is not robust against disorder and defects. Here, we propose a novel time-reversal symmetric topological insulator holding the synchronized in-gap edge states. To prevent the participation of bulk states, we introduce the time-reversal symmetry to detach the edge states from the bulk band, then the robust copropagation is realized through widening the band gap across a metal-insulator transition with anisotropic next-nearest-neighbor couplings. The time-reversal symmetry ensures the in-gap edge states with opposite momenta as the counterpropagating modes. The inversion symmetry protects the quantized polarization as a topological invariant. The synchronized in-gap edge states not only enrich the family of topological edge states, but also provide additional flexibility in the design of reconfigurable topological optical devices. Our findings open a new avenue for the tailored robust wave transport using the in-gap edge states for future acousto-optic topological metamaterials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
19 pages, 5 figures
Polydisperse polymer networks with irregular topologies
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-25 20:00 EDT
Jason Mulderrig, Michael Buche, Matthew Grasinger
The structure of polymer networks, defined by chain lengths and connectivity patterns, fundamentally influences their bulk properties. Despite decades of research, many open questions remain regarding structure-property relationships, particularly in heterogeneous networks. While existing polymer network models connect chain properties to emergent network behavior, they are often limited to monodisperse networks with regular connectivities, making the extension to heterogeneous systems an active area of research. In this work, we introduce a novel modeling framework that shifts the focus from individual polymer chains to cross-links and their connected chains as the fundamental unit of analysis. This perspective enables direct incorporation of structural heterogeneity by averaging over cross-links with different chain lengths and coordination numbers. We establish important connections between polymerization theory and statistical descriptors of network structure, providing key components of a theoretical foundation for predicting properties from the synthesis parameters. Our results demonstrate that increased variance in monomer numbers generally leads to network softening, while in bimodal networks, the onset of strain stiffening is controlled by shorter chains and the stiffening response is modulated by the ratio of short to long chains. By deriving closed-form approximations valid in both the limits of (1) small deformation and (2) finite deformation but with small polydispersity, we offer an efficient computational approach to modeling complex networks. This framework represents an advance toward the rational modeling and design of heterogeneous polymer networks with structures tailored for specific properties.
Soft Condensed Matter (cond-mat.soft)
Rapid and Scalable Synthesis of Alkali Metal-Intercalated C$_{60}$ Superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-25 20:00 EDT
Akira Iyo, Hiroshi Fujihisa, Yoshito Gotoh, Shigeyuki Ishida, Hiroshi Eisaki, Hiraku Ogino, Kenji Kawashima
Alkali metal-intercalated C$ {60}$ , $ A_3$ C{60}$ ($ A$ = K, Rb, Cs, and their combinations), holds significant potential for practical applications due to its high superconducting transition temperature (33 K), high upper critical field (900 kOe), and isotropic superconductivity. However, application-oriented research has been limited by the lack of an efficient $ A_3$ C_{60}$ synthesis process. In this study, we demonstrate a rapid and scalable synthesis of $ A_3$ C_{60}$ ($ A$ = K, Rb, and Cs$ _{1/3}$ Rb$ {2/3}$ ) via direct mixing of $ A$ and C$ {60}$ , realizing the fabrication of high-quality sintered $ A_3$ C{60}$ pellets within just 1 hour of heating at 200-300°C. The pellets exhibited large superconducting shielding volume fractions with sharp transitions, and the relationship between the lattice constant and transition temperature was in good agreement with previous reports. This direct mixing method enables simple and rapid production of large quantities of $ A_3$ C{60}$ , which is expected to accelerate research into applications such as superconducting wires and bulk magnets.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
11 pages, 4 figures, 1 table
Supercond. Sci. Technol. 38 (2025) 055013
Hilbert Transform Technique for Analyzing Mode I Crack Growth in an Pre- Stressed Monoclinic Crystalline Strip Under Punch Pressure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
Diksha, Soniya Chaudhary, Pawan Kumar Sharma
The crux of the present study is to analyze the Mode I crack propagation behavior in a pre-stressed monoclinic crystalline strip of finite thickness and infinite extent. The investigation focuses on the effects of collinear Griffith cracks and dynamic punch loading induced by plane wave propagation. The cracks are assumed to be in motion, and a Galilean transformation is employed to formulate the problem within a moving coordinate system. The boundary value problem is transformed into a system of coupled Cauchy-type singular integral equations, which are solved analytically using the Hilbert transform method. This approach yields elegant closed-form solutions for both the stress intensity factor and the crack opening displacement. The study considers two monoclinic crystalline materials, Lithium Niobate and Lithium Tantalate, and compares their behavior with that of an isotropic material to assess the role of material anisotropy. Numerical simulations and graphical analysis are performed for the crystalline materials with monoclinic symmetry to evaluate the influence of crack velocity, punch loading, material anisotropy, initial stress, and crack geometry on the fracture parameters. As a special case, the system is analyzed under the action of point loading from the punch pressure, and a comparative assessment is conducted between point loading and constant normal punch pressure. The results unveil critical insights into the dynamic fracture behavior of anisotropic materials under localized loading. This understanding enhances failure prediction in high-precision fields such as geomechanics, MEMS, surface acoustic devices, and biosensors.
Materials Science (cond-mat.mtrl-sci)
Thermally quenched metastable phase in the Ising model with competing interactions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
Hiroshi Oike, Hidemaro Suwa, Yasunori Takahashi, Fumitaka Kagawa
Thermal quenching has been used to find metastable materials such as hard steels and metallic glasses. More recently, quenching-based phase control has been applied to correlated electron systems that exhibit metal–insulator, magnetic or superconducting transitions. Despite the discovery of metastable electronic phases, however, how metastability is achieved through the degrees of freedom, which can vary even at low temperatures such as those of an electron, is unclear. Here, we show a thermally quenched metastable phase in the Ising model without conservation of magnetization by Monte Carlo simulations. When multiple types of interactions that stabilize different long-range orders are introduced, the ordering kinetics divergently slow toward low temperatures, meaning that the system will reach a low temperature without ordering if the cooling rate is high enough. Quantitative analysis of the divergent behavior suggests that the energy barrier for eliminating the local structure of competing orders is the origin of this metastability. Thus, the present simulations show that competing interactions play a key role in realizing metastability.
Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
Scalable Parallel Single-Electron Pumps in Silicon with Split-Source Control in the Nanoampere Regime
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
Gento Yamahata, Takase Shimizu, Katsuhiko Nishiguchi, Akira Fujiwara
Parallelizing single-electron pumps offers a promising route to achieving nanoampere-level currents crucial for quantum current standard applications. Achieving such current levels is essential for demonstrating the ultra-high accuracy of single-electron pumps below 0.1 ppm toward quantum metrology triangle experiments. In addition, improving the accuracy at this current range is also desirable for practical small-current measurements. However, nanoampere-level currents have not yet been achieved with parallel pumps, mainly due to challenges in optimizing operating conditions. Here, we propose a scalable and easily implementable parallelization method based on tunable-barrier single-electron pumps with split source electrodes. By tuning the source voltages, we successfully parallelize four single-electron pumps at 200 MHz and further demonstrate a current plateau exceeding 2 nA using three pumps at 2.1 GHz. The wide applicability of this parallelization technique opens a path toward advancing high-accuracy quantum current standards.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Observation of the Einstein-de Haas Effect in a Bose-Einstein condensate
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-25 20:00 EDT
Hiroki Matsui, Yuki Miyazawa, Ryoto Goto, Chihiro Nakano, Yuki Kawaguchi, Masahito Ueda, Mikio Kozuma
The Einstein-de Haas effect is a phenomenon in which angular momentum is transferred from microscopic spins to mechanical rotation of a rigid body. Here, we report the first observation of the Einstein-de Haas effect in a spinor-dipolar Bose-Einstein condensate where quantized vortices emerge in depolarized spinor components through coherent angular-momentum transfer from microscopic atomic spins to macroscopic quantized circulation. Experimental results clearly show that the spherical symmetry of the condensate is dynamically broken into the axisymmetry by an intrinsic magnetic dipole-dipole interaction.
Quantum Gases (cond-mat.quant-gas)
12 pages, 6 figures
Light-driven lattice metastability for enhanced superconductivity in FeSe/SrTiO3
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
Qiang Zou, Zhan Su, Andres Tellez Mora, Na Wu, Joseph Benigno, Christopher L. Jacobs, Aldo H. Romero, Subhasish Mandal, Yaxian Wang, Sheng Meng, Michael Weinert, Hua Zhou, Lian Li, Cheng Cen
Driven quantum materials with on demand properties controlled by external stimuli are critical for emergent quantum technology. In optically tunable superconducting heterostructures, the lattice responses at the buried interface may hold the key to the light susceptibility but is very challenging to detect. In this work, a nondestructive synchrotron-based X-ray scattering phase-retrieval technique is implemented in monolayer-FeSe/SrTiO3 heterostructures to capture the three-dimensional interfacial atomic displacements in-situ as the interface superconductivity is actively manipulated by light. It is found that the interlayer sliding between FeSe and SrTiO3 can drastically alter how the lattice responds to the light. In domains with selected stacking configurations, the interface transforms the very weak photoexcitation in SrTiO3 into significant Fe-atom displacements in FeSe and generate metastable interfacial structures that can lead to a persistent superconductivity enhancement. These findings demonstrate an effective strategy for achieving greatly amplified light-lattice coupling for efficient quantum phase manipulations at designed interfaces.
Materials Science (cond-mat.mtrl-sci)
A local quantized marker for topological magnons from circular dichroism
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
Baptiste Bermond, Anaïs Defossez, Nathan Goldman
The low-energy excitations of a spin system can display Bloch bands with non-trivial topological properties. While topological magnons can be identified through the detection of chiral propagating modes at the sample’s edge, an intriguing approach would be to directly probe their topological nature via localized measurements deep within the bulk. In this work, we introduce a quantized topological marker suitable for topological spin systems, which can be experimentally accessed by combining a local driven-dissipative preparation scheme with a circular-dichroic measurement. Demonstrated on a 2D ferromagnetic Heisenberg spin system incorporating Dzyaloshinskii-Moriya interactions, this method effectively maps a local Chern marker with single-site resolution while inherently accounting for magnon losses. Our work offers a general strategy to access local topological markers in bosonic settings within a driven-dissipative framework.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
9 pages, 4 figures
NMR chemical shielding for solid-state systems using spin-orbit coupled ZORA GIPAW
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
T. Speelman, M.-T. Huebsch, R.W.A. Havenith, M. Marsman, G.A. de Wijs
We present an implementation of spin-orbit coupling (SOC) for the computation of nuclear magnetic resonance (NMR) chemical shielding tensors within linear response theory. Our implementation in the Vienna {\it Ab initio} Simulation Package (VASP) is tailored to solid-state systems by employing periodic boundary conditions and the gauge-including projector augmented waves (GIPAW) approach. Relativistic effects are included on the level of the zeroth-order regular approximation (ZORA). We discuss the challenges posed by the PAW partial wave basis in describing SOC regarding chemical shielding tensors. Our method is in good agreement with existing local-basis ZORA implementations for a series of Sn, Hg, and Pb molecules and cluster approximations for crystalline systems.
Materials Science (cond-mat.mtrl-sci)
Structural design and multiple magnetic orderings of the intergrowth compound Eu$_2$CuMn$_2$P$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
Xiyu Chen, Ziwen Wang, Wuzhang Yang, Jia-Yi Lu, Zhiyu Zhou, Zhi Ren, Guang-Han Cao, Shuai Dong, Zhi-Cheng Wang
We report the design, synthesis, crystal structure, and physical properties of a layered intergrowth compound, Eu$ _2$ CuMn$ _2$ P$ _3$ . The structure of Eu$ _2$ CuMn$ _2$ P$ _3$ features an alternating arrangement of hexagonal EuCuP block layers and trigonal EuMn$ 2$ P$ 2$ block layers, interconnected through shared Eu planes. This structural hybridization leads to multiple magnetic orderings in Eu$ 2$ CuMn$ 2$ P$ 3$ : weak antiferromagnetic (AFM) ordering of Mn at $ T\mathrm{N}^\mathrm{Mn}$ = 80 K, AFM ordering of Eu at $ T\mathrm{N}^\mathrm{Eu}$ = 29 K, a spin-reorientation transition at $ T\mathrm{SR}$ = 14.5 K, and weak ferromagnetism below $ T\mathrm{N}^\mathrm{Mn}$ . The spin configurations at different temperature regions were discussed based on the calculations of magnetic energies for various collinear arrangements. Resistivity measurements reveal a pronounced transition peak at $ T\mathrm{N}^\mathrm{Eu}$ , which is suppressed in the presence of a magnetic field, resulting in a significant negative magnetoresistance effect. The computed semimetallic band structure, characterized by a small density of states at the Fermi level, aligns well with experimental observations. The successful synthesis of Eu$ _2$ CuMn$ _2$ P$ _3$ and its fascinating magnetic properties highlight the effectiveness of our block-layer design strategy. By assembling magnetic block layers of compounds with compatible crystal symmetries and closely matched lattice parameters, this approach opens exciting avenues for discovering layered materials with unique magnetic behaviors.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Emergence of the logarithmic average phonon frequency in the superconducting critical temperature formula
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-25 20:00 EDT
Nattawut Natkunlaphat, Pakin Tasee, Udomsilp Pinsook
We analytically demonstrate the essential role of the logarithmic average phonon frequency in describing the superconducting critical temperature, directly from a predictive function. The current study assumes that the Eliashberg spectral function follows the Debye model in the low frequency spectrum, whereas contributions from optical phonons dominate outside this range. Our findings confirm that, under a specific condition, we obtained a formula for superconducting transition temperature. Furthermore, we compared our formula with the Allen-Dynes formula and its modified version, and the exact solutions. They reveal notable correlations.
Superconductivity (cond-mat.supr-con)
22 pages, 2 figures
Optimizing thermoelectric performance of graphene antidot lattices via quantum transport and machine-learning molecular dynamics simulations
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
Yang Xiao, Yuqi Liu, Zihan Tan Bohan Zhang, Ke Xu, Zheyong Fan, Shunda Chen, Shiyun Xiong, Haikuan Dong
Thermoelectric materials, which can convert waste heat to electricity or be utilized as solid-state coolers, hold promise for sustainable energy applications. However, optimizing thermoelectric performance remains a significant challenge due to the complex interplay between electronic and thermal transport properties. In this work, we systematically optimize $ ZT$ in graphene antidot lattices (GALs), nanostructured graphene sheets with periodic nanopores characterized by two geometric parameters: the hexagonal unit cell side length $ L$ and the antidot radius $ R$ . The lattice thermal conductivity is determined through machine-learned potential-driven molecular dynamics (MD) simulations, while electronic transport properties are computed using linear-scaling quantum transport in combination with MD trajectories based on a bond-length-dependent tight-binding model. This method is able to account for electron-phonon scattering, allowing access to diffusive transport in large-scale systems, overcoming limitations of previous methods based on nonequilibrium Green function formalism. Our results show that the introduction of the antidots effectively decouples lattice and electronic transport and lead to a favorable and significant violation of the Wiedemann-Franz law. We find that optimal $ ZT$ values occur in GALs with intermediate $ L$ and $ R$ , closely correlated with peak power factor values. Notably, thermoelectric performance peaks near room temperature, with maximal $ ZT$ values approaching 2, highlighting GALs as promising candidates for high-performance thermoelectric energy conversion.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
10 pages, 7 figures
The need for statistical physics in Africa: perspective and an illustration in drug delivery problems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-25 20:00 EDT
Mtabazi G. Sahini, Isaac Onoka, Said A.H. Vuai, Édgar Roldán, Hulda S. Swai, Daniel M. Shadrack
The development of statistical physics in Africa is in its nascent stages, yet its application holds immense promise for advancing emerging research trends on the continent. This perspective paper, a product of a two-week workshop on biophysics in Morogoro (Tanzania), aims to illuminate the potential of statistical physics in regional scientific research. We employ in-silico atomistic molecular dynamics simulations to investigate the loading and delivery capabilities of lecithin nanolipids for niclosamide, a poorly water-soluble drug. Our simulations reveal that the loading capacity and interaction strength between lecithin nanolipids and niclosamide improve with increased lecithin concentrations. We perform a free-energy landscape analysis which uncovers two distinct metastable conformations of niclosamide within both the aqueous phase and the lecithin nanolipids. Over a simulation period of half a microsecond, lecithin nanolipids self-assemble into a spherical monolayer structure, providing detailed atomic-level insights into their interactions with niclosamide. These findings underscore the potential of lecithin nanolipids as efficient drug delivery systems.
Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph), Chemical Physics (physics.chem-ph), Physics and Society (physics.soc-ph)
8 pages, 7 figures, submitted to EPL as perspective article
Consistency between the Green-Kubo formula and Lorentz model for predicting the infrared dielectric function of polar materials
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
Wei-Zhe Yuan, Yangyu Guo, Hong-Liang Yi
Accurate prediction of infrared dielectric functions in polar materials is fundamental for thermal and photonic applications, yet it remains unexplored whether the two main methods, Green-Kubo formula and Lorentz model, can give unified predictions. In this work, we present a detailed comparison of these two approaches using MgO and LiH as prototypical cases employing both empirical rigid ion model (RIM) and machine learning potential (MLP). We demonstrate that the conventional Lorentz model fails to capture the multi-phonon absorption inherent in Green-Kubo method, which can be resolved via using the phonon self-energy as a generalization of the usual linewidth. In addition, with RIM, a correction factor is required in the ionic contribution to infrared response to account for the electronic polarization effect, which is yet captured by MLP using the Born effective charges for calculating dipole moment. The present benchmark study thus enables cross-validation of dielectric function calculations while providing mechanistic insights into the polarization dynamics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
14 pages, 12 figures
Magnetically disordered ground state in the triangular-lattice antiferromagnets Rb$_3$Yb(VO$_4$)$_2$ and Cs$_3$Yb(VO$_4$)$_2$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-25 20:00 EDT
Zhen Ma, Yingqi Chen, Zhongtuo Fu, Shuaiwei Li, Xin-An Tong, Hong Du, Jan Peter Embs, Shuhan Zheng, Yongjun Zhang, Meifeng Liu, Ruidan Zhong, Jun-Ming Liu, Jinsheng Wen
Quantum spin liquids(QSLs) represent a unique quantum disordered state of matter that hosts long-range quantum entanglement and fractional excitations. However, structural disorder resulting from site mixing between different types of ions usually arises in real QSL candidates, which is considered as an obstacle to gain the insight into the intrinsic physics. Here, we have synthesized two new rare-earth compounds Rb$ _3$ Yb(VO$ _4$ )$ _2$ and Cs$ _3$ Yb(VO$ _4$ )$ _2$ . X-ray diffractions reveal a perfect triangular-lattice structure with no detectable disorder. Magnetic susceptibility measurements do not capture any phase transition or spin freezing down to 1.8K. A fit to low-temperature data indicates dominant antiferromagnetic interactions with the Curie-Weiss temperature of -1.40K and -0.43K for Rb$ _3$ Yb(VO$ _4$ )$ _2$ and Cs$ _3$ Yb(VO$ _4$ )$ _2$ , respectively. Specific heat results show no sign of long-range magnetic order down to $ \sim$ 0.1K either, but only a Schottky anomaly that is continuously mediated by the external magnetic fields. Additionally, inelastic neutron scattering is employed to detect low-energy spin excitations in Rb$ _3$ Yb(VO$ _4$ )$ _2$ . The absence of magnetic excitation signals as well as static magnetic order down to 97mK aligns with the results from magnetic susceptibility and specific heat. Collectively, these findings point to a quantum disordered ground state with persistent spin dynamics, reminiscent of QSL behaviors. Our work provides a promising platform for further exploration of quantum magnetism in this new disorder-free system.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
11 pages, 5 figures
Phys. Rev. B 111, 155141 (2025)
New self-organized benzo[b]thiophene-based materials for GHz applications
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-25 20:00 EDT
Agnieszka Mieczkowska, Jakub Herman, Natan Rychlowicz, Monika Zajac, Piotr Harmata
This research delves into the synthesis and characterization of novel liquid crystal compounds derived from benzo[b]Ithiophene cores, focusing on their potential applications in microwave technology. Two synthetic strategies were developed to construct rigid cores, resulting in the successful synthesis of ten compounds with varied terminal groups and lateral substituents. Correlations between molecular structure and mesomorphic properties were elucidated through extensive comparative analysis. Birefringence measurements and quantum chemical calculations further provided insights into the optical properties and polarizability anisotropy of the synthesized compounds. The results highlight the influence of structural diversity on the compounds’ suitability for microwave applications. Specifically, compounds featuring carbon-carbon triple bonds and polar terminal groups demonstrated enhanced birefringence and polarizability values, indicating their potential in microwave device fabrication. This study underscores the importance of molecular design in optimizing liquid crystal materials for advanced technological applications.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
This work was supported by the National Centre of Science MINIATURA 6 number 2022/06/X/ST5/00700
Liquid Crystals, 2024, 51, 1256-1269
Surface morphology and thickness variation estimation of zeolites via electron ptychography
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
Enci Zhang, Zhuoya Dong, Xubin Han, Jianhua Zhang, Yanhang Ma, Huaidong Jiang
Zeolites, as representative porous materials, possess intricate three-dimensional frameworks that endow them with high surface areas and remarkable catalytic properties. There are a few factors that give a huge influence on the catalytic properties, including the size and connectivity of these three-dimensional channels and atomic level defects. In additional to that, the surface morphology and thickness variation of zeolites particles are essential to their catalytic performances as well. However, it is a significant challenge to characterize these macroscopic properties of zeolites using conventional techniques due to their sensitivity to electron beams. In this study, we introduce surface-adaptive electron ptychography, an advanced approach based on multi-slice electron ptychography, which enables high-precision reconstruction of both local atomic configurations and global structural features in zeolite nanoparticles. By adaptively optimizing probe defocus and slice thickness during the reconstruction process, SAEP successfully resolves surface morphology, thickness variations and atomic structure simultaneously. This integrated framework facilitates a direct and intuitive correlation between zeolite channel structures and particle thickness. Our findings open new pathways for large-scale, comprehensive structure property analysis of beam-sensitive porous materials, deepening the understanding of their catalytic behavior.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
19 pages, 6 figures
Current phase relation in a planar graphene Josephson junction with spin-orbit coupling
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
Federico Bonasera, Giuseppe A. Falci, Elisabetta Paladino, Francesco M.D. Pellegrino
We study a graphene Josephson junction where the inner graphene layer is subjected to spin-orbit coupling by proximity effect. This could be achieved, for example, by growing the graphene layer on top of a transition metal dichalcogenide, such as WS$ _2$ . Here, we focus on the ballistic, wide, and short junction limits and study the effects of the spin-orbit interaction on the supercurrent. In particular, we analyze the current phase relation using an analytical approach based on the continuum model. We find combinations of types of spin-orbit coupling that significantly suppress the supercurrent by opening a gap in the graphene band structure. At the same time, other combinations enhance it, acting as an effective spin-valley resolved chemical potential. Moreover, we find that a strong Rashba spin-orbit coupling leads to a junction with a highly voltage tunable harmonic content.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)
8 pages, 3 figures
Permeation and thermal desorption model of hydrogen in steel: a sensitivity analysis
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
This work presents a fully physical model of the hydrogen diffusion and trapping kinetics in metals, integrating permeation and thermal desorption within a unified framework. Based on the McNabb and Foster approach, it requires only binding energy and number density of trap sites. It correctly reproduces the physics of the system and the results of the analytical solutions of the permeation kinetics. It is also capable of reproducing thermal desorption spectra with considerable accuracy. The sensitivity analysis has elucidated the relationships among the processing conditions and the parameters commonly used to characterize permeation and thermal desorption experiments. An equation empirically derived from the simulation results, expressing the dependence of time lag in desorption on specimen thickness, number density of occupied trap sites, and cathodic concentration, is proposed. In summary, the model represents a valuable tool in supporting the interpretation and rationalization of experiments also from a quantitative viewpoint.
Materials Science (cond-mat.mtrl-sci)
Quasi-particle residue and charge of the one-dimensional Fermi polaron
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-25 20:00 EDT
Giuliano Orso, Lovro Barišić, Ekaterina Gradova, Frédéric Chevy, Kris Van Houcke
We consider a mobile impurity coupled to an ideal Fermi gas in one spatial dimension through an attractive contact interaction. We calculate the quasi-particle residue $ Z$ exactly, based on Bethe Ansatz and diagrammatic Monte Carlo methods, and with varational Ansatz up to one particle-hole excitation of the Fermi sea. We find that the exact quasi-particle residue vanishes in the thermodynamic limit as a power law in the number of particles, consistent with the Luttinger-liquid paradigm and the breakdown of Fermi-liquid theory. The variational Ansatz, however, predicts a finite value of $ Z$ , even in the thermodynamic limit. We also study how the presence of the impurity affects the density of the spin-up sea by calculating the pair correlation function. Subtracting the homogeneous background and integrating over all distances gives the charge $ Q$ . This charge turns out to grow continuously from 0 at zero coupling to 1 in the strong-coupling limit. The varational Ansatz predicts $ Q=0$ at all couplings. So, although the variational Ansatz has been shown to be remarkably accurate for the energy and the effective mass, it fails even qualitatively when predicting $ Z$ and the pair correlation function in the thermodynamic limit.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
THz Emission from Spintronic Microstructure
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
Abbas Ghaffari, Malek Abdelsamei, Puja Thapa, Seiji Mita, Ramón Collazo, Kenan Gundogdu, Dali Sun, Qing Gu
Recent advancements in spintronics have opened a new avenue in terahertz (THz) radiation sources that may outperform the traditional contact-based metallic counterparts. Inspired by the generation of broadband spintronic THz signals at the interface of a ferromagnet and ultrawide bandgap semiconductors, here we investigated the generation of THz radiation from micro-structured heterostructures of a metallic ferromagnet (Ni80Fe20) and an ultrawide bandgap semiconductor (AlGaN/GaN) that contains a layer of 2D electron gas. By precisely tailoring the dimension of the subwavelength pillars of a THz device, the micro-structured spintronic THz emitter can achieve up to more than three times higher emission intensity compared to that of the un-patterned counterpart. Our study advances the development of the next generation of spintronic THz sources that allow a tailored emission frequency and intensity control and, further, are compatible with existing integrated wide-bandgap semiconductor circuits.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Dynamical gauge invariance of statistical mechanics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-25 20:00 EDT
Johanna Müller, Florian Sammüller, Matthias Schmidt
We investigate gauge invariance against phase space shifting in nonequilibrium systems, as represented by time-dependent many-body Hamiltonians that drive an initial ensemble out of thermal equilibrium. The theory gives rise to gauge correlation functions that characterize spatial and temporal inhomogeneity with microscopic resolution on the one-body level. Analyzing the dynamical gauge invariance allows one to identify a specific localized shift gauge current as a fundamental nonequilibrium observable that characterizes particle-based dynamics. When averaged over the nonequilibrium ensemble, the shift current vanishes identically, which constitutes an exact nonequilibrium conservation law that generalizes the Yvon-Born-Green equilibrium balance of the vanishing sum of ideal, interparticle, and external forces. Any given observable is associated with a corresponding dynamical hyperforce density and hypercurrent correlation function. An exact nonequilibrium sum rule interrelates these one-body functions, in generalization of the recent hyperforce balance for equilibrium systems. We demonstrate the physical consequences of the dynamical gauge invariance using both harmonically confined ideal gas setups, for which we present analytical solutions, and molecular dynamics simulations of interacting systems, for which we demonstrate the shift current and hypercurrent correlation functions to be accessible both via finite-difference methods and via trajectory-based automatic differentiation. We show that the theory constitutes a starting point for developing nonequilibrium reduced-variance sampling algorithms and for investigating thermally-activated barrier crossing.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
24 pages, 7 figures
Time-resolved dynamics of GaN waveguide polaritons
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
Loïc Méchin, François Médard, Joël Leymarie, Sophie Bouchoule, Blandine Alloing, Jesús Zúñiga-Pérez, Pierre Disseix
We implement a new experimental approach to directly measure the lifetime of guided polaritons arising from the strong-coupling of GaN excitons and the guided photonic modes of a slab waveguide. Using a Fourier imaging setup, combined with spatial filtering of the emission, the emission associated to polaritonic modes with well-defined propagation constants can be selectively analyzed in the temporal domain. By directing it to the entrance slit of a streak camera, time-resolved photoluminescence (TRPL) measurements along the polariton dispersion branch were performed at 40 K, enabling to assess the time decay of polariton modes. By combining this information with the photonic/excitonic fraction corresponding to each polariton mode, extracted from a coupled-oscillators model that indicate a Rabi splitting of $ \Omega$ = 80 meV, we could extract the photon lifetime in the waveguide $ \tau_\gamma, =, 3\pm 1$ ps. This corresponds to a record $ Q$ -factor in the UV of 16 000. The excitonic reservoir lifetime, which contributes to polariton formation, was determined through TRPL measurements on excitonic luminescence. Finally, measurements conducted at lower temperature highlight secondary feeding mechanisms for the guided polaritonic mode, either via photon recycling from the AlGaN cladding layer or through resonant injection of photons from transitions below the band gap.
Materials Science (cond-mat.mtrl-sci)
Thermal Hall conductivity in the strongest cuprate superconductor: Estimate of the mean free path in the trilayer cuprate HgBa$_2$Ca$_2$Cu$3$O${8 + δ}$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-25 20:00 EDT
Munkhtuguldur Altangerel, Quentin Barthélemy, Étienne Lefrançois, Jordan Baglo, Manel Mezidi, Gaël Grissonnanche, Ashvini Vallipuram, Emma Campillo, Anne Forget, Dorothée Colson, Ruixing Liang, D. A. Bonn, W. N. Hardy, Cyril Proust, Louis Taillefer
The thermal Hall conductivity of the trilayer cuprate HgBa$ _2$ Ca$ _2$ Cu$ _3$ O$ _{8+\delta}$ (Hg1223) - the superconductor with the highest critical temperature $ T_c$ at ambient pressure - was measured at temperatures down to 2 K for three dopings in the underdoped regime ($ p$ = 0.09, 0.10, 0.11). By combining a previously introduced simple model and prior theoretical results, we derive a formula for the inverse mean free path, $ 1 / \ell$ , which allows us to estimate the mean free path of $ d$ -wave quasiparticles in Hg1223 below $ T_c$ . We find that $ 1 / \ell$ grows as $ T^3$ , in agreement with the theoretical expectation for a clean $ d$ -wave superconductor. Measurements were also conducted on the single layer mercury-based cuprate HgBa$ _2$ CuO$ _{6+\delta}$ (Hg1201), revealing that the mean free path in this compound is roughly half that of its three-layered counterpart at the same doping ($ p$ = 0.10). This observation can be attributed to the protective role of the outer planes in Hg1223, which results in a more pristine inner plane. We also report data in an ultraclean crystal of YBa$ _2$ Cu$ _3$ O$ _y$ (YBCO) with full oxygen content $ p$ = 0.18, believed to be the cleanest of any cuprate, and find that $ \ell$ is not longer than in Hg1223.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Programmable glassy dynamics using tunable disorder in tweezer arrays
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-25 20:00 EDT
Kaustav Mukherjee, Grant W. Biedermann, Robert J. Lewis-Swan
We propose a unifying framework for non-equilibrium relaxation dynamics in ensembles of positionally disordered interacting quantum spins based on the statistical properties, such as mean and variance, of the underlying disorder distribution. Our framework is validated through extensive exact numerical calculations and we use it to disentangle and understand the importance of dimensionality and interaction range for the observation of glassy (i.e., sub-exponential) decay dynamics. Leveraging the deterministic control of qubit positioning enabled by modern tweezer array architectures, we also introduce a method (``J-mapping’’) that can be used to emulate the relaxation dynamics of a disordered system with arbitrary dimensionality and interaction range in bespoke one-dimensional arrays. Our approach paves the way towards tunable relaxation dynamics that can be explored in quantum simulators based on arrays of neutral atoms and molecules.
Quantum Gases (cond-mat.quant-gas), Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Physics (quant-ph)
8 pages, 7 figures, 1 table
Long-range four-body interactions in the Hamiltonian mean field model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-25 20:00 EDT
Qiang Zhang, Yu Xue, Haojie Luo, Bingling Cen
In this paper, a Hamiltonian mean field model with long-range four-body interactions is proposed. The model describes a long-range mean-field system in which N unit-mass particles move on a unit circle. Each particle theta_i interacts with any three other particles through an infinite-range cosine potential with an attractive interaction (epsilon > 0). By applying a method that remaps the average phase of global particle pairs onto a new unit circle, and using the saddle-point technique, the partition function is solved analytically after introducing four-body interactions, yielding expressions for the free energy f and the energy per particle U. These results were further validated through numerical simulations. The results show that the system undergoes a second-order phase transition at the critical energy U_c. Specifically, the critical energy corresponds to U_c = 0.32 when the coupling constant epsilon = 5, and U_c = 0.63 when epsilon = 10. Finally, we calculated the system’s largest Lyapunov exponent lambda and kinetic energy fluctuations Sigma through numerical simulations. It is found that the peak of the largest Lyapunov exponent lambda occurs slightly below the critical energy U_c, which is consistent with the point of maximum kinetic energy fluctuations Sigma. And there is a scaling law of Sigma / N^(1/2) proportional to lambda between them.
Statistical Mechanics (cond-mat.stat-mech)
Metal-insulator transitions in pyrochlore oxides
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-25 20:00 EDT
Yoshinori Tokura, Yukitoshi Motome, Kentaro Ueda
Pyrochlore oxides with chemical formula of A2B2O7 exhibit a diverse range of electronic properties as a representative family of quantum materials. These properties mostly stem from strong electron correlations at the transition metal B site and typical geometrical frustration effects on the pyrochlore lattice. Furthermore, the coupling between the magnetic moments of the rare-earth A site and the conduction electrons at the B site, along with the relativistic spin-orbit coupling particularly affecting the 4d/5d electrons at the B site, gives rise to the topological characteristics of the correlated electrons. This review paper focuses on the metal-insulator transitions in pyrochlore oxides as evidence of the strong electron correlation, which is highlighted as a rich source of intriguing charge dynamics coupled with frustrated spin-orbital entangled magnetism.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Submitted to Reports on Progress in Physics (under review)
Real-space superconducting properties in the atomically-thin limit: Ab initio approach and its application to Josephson junctions
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-25 20:00 EDT
Jonas Bekaert, Mikhail Petrov, Milorad V. Milošević
Real-space superconducting properties are increasingly important to characterize low-dimensional, layered, and nanostructured materials. Here, we present a method to extract the real-space superconducting order parameter from the superconducting gap spectrum obtained via anisotropic Migdal-Eliashberg calculations, using the Bloch wave functions of the Fermi states. We apply this approach to a selection of atomically thin material systems. Our analysis of gallenene, a monolayer of gallium atoms, shows that its planar and buckled phases exhibit distinct superconducting order parameter behaviors, shaped by their structural and electronic properties. Furthermore, we demonstrate that our real-space approach is exceptionally suited to identify and characterize Josephson junctions made from van der Waals materials. Our examination of a bilayer of NbSe$ _2$ reveals that the van der Waals gap acts as an intrinsic weak link between the superconducting NbSe$ _2$ layers. Therefore, a bilayer of NbSe$ _2$ represents one of the thinnest and most tunable Josephson junction architectures, with potential applications in quantum devices. Our findings underscore the utility of transformation into real-space in understanding superconducting properties through ab initio calculations.
Superconductivity (cond-mat.supr-con)
Study on P-Type Doping of Mid-Wave and Long-Wave Infrared Mercury Cadmium Telluride
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
Arash Dehzangi, John Armstrong, Chris Schaake, Mark Skokan, Tyler Morrison, Justin Wilks, Sameer Ajmera, Mike Kinch
We present in depth study of p-type doping concentration of mid-wave infrared (MWIR) and long-wave infrared (LWIR) mercury cadmium Telluride (HgCdTe) thin films. Annealing time was changed under specific conditions to achieve a stable copper (Cu) doping concentration for HgCdTe thin films. Both MWIR and LWIR HgCdTe material were grown by molecular beam epitaxy (MBE), where different trends were observed between LWIR and MWIR HgCdTe thin films by increasing anneal time. We also report the impact of different thickness (4 micron, 6 micron and 9 micron) along with annealing time on doping level of LWIR HgCdTe thin films.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Bandstructure of a coupled BEC-cavity system: effects of dissipation and geometry
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-25 20:00 EDT
David Baur, Simon Hertlein, Alexander Baumgärtner, Justyna Stefaniak, Tilman Esslinger, Gabriele Natale, Tobias Donner
We present a theoretical model for a transversally driven Bose-Einstein condensate coupled to an optical cavity. We focus on the interplay between different coherent couplings, which can trigger a structural phase transition, known as the superradiant phase transition. Our approach, based on band structure theory and a mean-field description, enables a comprehensive analysis of the nature of the system’s excited modes, precursing the phase transitions. By incorporating dissipative couplings, intrinsic to these systems, we find non-Hermitian phenomena such as the coalescence of crossing precursor modes and the emergence of exceptional points (EPs). The general formulation of our model allows us to explain the role of an angle between transverse pump and the cavity deviating from $ 90^\circ$ . This offers us a unified perspective on the plethora of different implementations of such systems.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
16 pages, 14 figures
Synchronization of Quasi-Particle Excitations in a Quantum Gas with Cavity-Mediated Interactions
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-25 20:00 EDT
Gabriele Natale, Alexander Baumgärtner, Justyna Stefaniak, David Baur, Simon Hertlein, Dalila Rivero, Tilman Esslinger, Tobias Donner
Driven-dissipative quantum systems can undergo transitions from stationary to dynamical phases, reflecting the emergence of collective non-equilibrium behavior. We study such a transition in a Bose-Einstein condensate coupled to an optical cavity and develop a cavity-assisted Bragg spectroscopy technique to resolve its collective modes. We observe dissipation-induced synchronization at the quasiparticle level, where two roton-like modes coalesce at an exceptional point. This reveals how dissipation microscopically drives collective dynamics and signals a precursor to a dynamical phase transition.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
10 pages, 4 figures
Novel Heusler Materials for Spintronic Applications: Growth, Characterizations and Applications
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
Spintronics is a rapidly evolving technology that utilizes the spin of electrons along with their charge to enable high speed, low power and non volatile electronic devices. The development of novel materials with tailored magnetic and electronic properties is critical to exploit the full potential of spintronic applications. Among these, Heusler alloys stand out due to their tunable multifunctional properties. This review presents a comprehensive overview of various Heusler based materials including half metallic ferromagnets, spin gapless semiconductors, magnetic semiconductors, spin semimetals, and nearly zero moment materials focusing on their synthesis, structural and magnetic characterizations, and transport behavior. The role of crystal structure, and structural disorder in governing their magnetic and electronic properties is discussed in detail. Emphasis is placed on experimental results and their implications for spintronic devices. By bringing together recent advancements, the review highlights the critical role of Heusler alloys in advancing the next-generation spintronic technologies and outlines future directions for their integration in practical applications.
Materials Science (cond-mat.mtrl-sci)
44 pages, 17 figures
Spall strength of symmetric tilt grain boundaries in 6H silicon carbide
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-25 20:00 EDT
Characterizing microstructural effects on the dynamical response of materials is challenging due to the extreme conditions and the short timescales involved. For example, little is known about how grain boundary characteristics affect spall strength. This study explores 6H-SiC bicrystals under shock waves via large-scale molecular dynamics simulations. We focused on symmetric tilt grain boundaries with a wide range of misorientations and found that spall strength and dynamical fracture surface energy are strongly affected by the grain boundary microstructure, especially the excess free volume. Grain boundary energy also plays a considerable role. As expected, low-angle grain boundaries tend to have higher spallation strengths. We also extracted cohesive models for the dynamical strength of bulk systems and grain boundaries that can be used in continuum simulations.
Materials Science (cond-mat.mtrl-sci)
Bringing light into the Landau-Lifshitz-Gilbert equation: Consequences of its fractal non-Markovian memory kernel for optically induced magnetic inertia and magnons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
Felipe Reyes-Osorio, Branislav K. Nikolic
The Landau-Lisfhitz-Gilbert (LLG) equation has been the cornerstone of modeling the dynamics of localized spins, viewed as classical vectors of fixed length, within nonequilibrium magnets. When light is employed as the nonequilibrium drive, the LLG equation must be supplemented with additional terms that are usually conjectured using phenomenological arguments for direct opto-magnetic coupling between localized spins and (real or effective) magnetic field of light. However, direct coupling of magnetic field to spins is 1/c smaller than coupling of light and electrons; or both magnetic and electric fields are too fast for slow classical spins to be able to follow them. Here, we displace the need for phenomenological arguments by rigorously deriving an extended LLG equation via Schwinger-Keldysh field theory (SKFT). Within such a theory, light interacts with itinerant electrons, and then spin current carried by them exerts spin-transfer torque onto localized spins, so that when photoexcited electrons are integrated out we arrive at a spin-only equation. Unlike the standard phenomenological LLG equation with local-in-time Gilbert damping, our extended one contains a non-Markovian memory kernel whose plot within the plane of its two times variables exhibits fractal properties. By applying SKFT-derived extended LLG equation, as our central result, to a light-driven ferromagnet as an example, we predict an optically induced magnetic inertia term. Its magnitude is governed by spatially nonlocal and time-dependent prefactor, leading to excitation of coherent magnons at sharp frequencies in and outside of the band of incoherent (or thermal) magnons.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 3 figures, 107 references
Zeptosecond free-electron compression through temporal lensing
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
Xin Jin, Cruz I. Velasco, F. Javier García de Abajo
The pursuit of ever-shorter time scales is a frontier in modern physics, exemplified by the synthesis of attosecond light pulses – an achievement made possible by coherently superimposing a broad range of photon energies, as required by the uncertainty principle. However, extending this progress into the zeptosecond regime poses significant challenges, as it demands phase-correlated optical spectra spanning hundreds of electronvolts. In this context, electrons offer a compelling alternative to light because they can be coherently manipulated to form broad energy superpositions, as demonstrated by the generation of attosecond pulses in ultrafast electron microscopes. Here, we propose a practical scheme for compressing free electrons into the zeptosecond domain by modulating their wave functions using suitably tailored broadband light fields. Building on recent advances in {free-electron–light–matter} interactions, our method introduces the concept of temporal lensing – an extension of conventional optical lensing to the time domain – to produce electron pulses with arbitrarily short durations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
18 pages, 9 figures, 41 references
Demagnetization in micromagnetics: magnetostatic self-interactions of bulk chiral magnetic skyrmions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
It is known that the magnetization in a ferromagnet induces an internal demagnetizing magnetic field. This, in-turn, generates a magnetostatic self-energy, coming from dipole-dipole interactions. In general, this energy is singular and intrinsically non-local. However, one can introduce a magnetic scalar potential associated with the demagnetizing field. We show that computation of the magnetic potential can be achieved by solving Poisson’s equation where the source is the divergence of the magnetization. Furthermore, we determine the variation of the magnetostatic self-energy and its associated back-reaction on the magnetization. Then, we present a theoretical study of the effect of the long-range dipolar interaction on magnetic skyrmion textures in the bulk of chiral ferromagnetic materials with the Dzyaloshinskii–Moriya interaction. It is observed that the demagnetizing dipolar self-interaction can stabilize antiskyrmion crystals in Heusler compounds.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages, 4 figures
Flexoelectric polarization in chiral liquid crystals: electrostatic self-interactions of topological defects
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-25 20:00 EDT
The presence of topological defects in apolar chiral liquid crystals cause orientational distortions, leading to non-uniform strain. This non-uniform strain generates an electric polarization response due to the flexoelectric effect, which induces an internal electric field. Associated to this electric field is an electrostatic self-energy, which has a back-reaction on the director field. Calculation of this internal electric field and its resulting back-reaction on the director field is complicated. We propose a method to do such, adapting a method recently developed to study the magnetostatic self-interaction effect on skyrmions in chiral ferromagnets. Bloch skyrmions in chiral magnets are solenoidal and are unaffected by the magnetostatic self-interaction. However, Bloch skyrmions in liquid crystals yield non-solenoidal flexoelectric polarization and, thus, are affected by the electrostatic self-interaction. Additionally, as the flexoelectric coefficients are increased in strength, a transition from a hopfion to a skyrmion is observed in three-dimensional confined systems.
Soft Condensed Matter (cond-mat.soft)
16 pages, 5 figures
Josephson anomalous vortices
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-25 20:00 EDT
Dan Crawford, Stefan Ilić, Pauli Virtanen, Tero T. Heikkilä
We show that vortices with circulating current, related with odd-frequency triplet pairing, appear in Josephson junctions where the barrier is a weak ferromagnet with strong spin-orbit coupling. By both symmetry analysis and microscopic methods we show that there is an additional term - a rotary invariant - in the superconducting free energy which allows for magnetoelectric effects even when the previously considered Lifshitz invariant vanishes. We show that the size, shape, and position of these vortices can be controlled by manipulating Rashba spin-orbit coupling in the weak link, via gates, and we suggest that these vortices could be detected via scanning magnetometry techniques. We also show that the transverse triplet components of the superconducting correlations can form a texture.
Superconductivity (cond-mat.supr-con)
7 pages, 4 figures
Nanoscale infrared and microwave imaging of stacking faults in multilayer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-25 20:00 EDT
Ludwig Holleis, Liam Cohen, Noah Samuelson, Caitlin L. Patterson, Ysun Choi, Marco Valentini, Owen Sheekey, Youngjoon Choi, Jiaxi Zhou, Hari Stoyanov, Takashi Taniguchi, Kenji Watanabe, Qichi Hu, Jin Hee Kim, Cassandra Phillips, Peter De Wolf, Andrea F. Young
Graphite occurs in a range of metastable stacking orders characterized by both the number and direction of shifts between adjacent layers by the length of a single carbon-carbon bond. At the extremes are Bernal (or ABAB...'') stacking, where the direction of the interlayer shift alternates with each layer, and rhombohedral (or ABCABC…’’) stacking order where the shifts are always in the same direction. However, for an N-layer system, there are in principle $ N-1$ unique metastable stacking orders of this type. Recently, it has become clear that stacking order has a strong effect on the low energy electronic band structure with single-layer shifts completely altering the electronic properties. Most experimental work has focused on the extremal stacking orders in large part due to the difficulty of isolating and identifying intermediate orders. Motivated by this challenge, here we describe two atomic force microscopy (AFM) based techniques to unambiguously distinguish stacking orders and defects in graphite flakes. Photo-thermal infrared atomic force microscope (AFM-IR) is able to distinguish stacking orders across multiple IR wavelengths and readily provides absolute contrast via IR spectral analysis. Scanning microwave impedance microscopy (sMIM) can distinguish the relative contrast between Bernal, intermediate and rhombohedral domains. We show that both techniques are well suited to characterizing graphite van der Waals devices, providing high contrast determination of stacking order, subsurface imaging of graphene flakes buried under a hexagonal boron nitride (hBN) dielectric layer, and identifying nanoscale domain walls. Our results pave the way for the reliable fabrication of graphene multilayer devices of definite interlayer registry.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Emergent fractals in dirty topological crystals
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-04-25 20:00 EDT
Non-trivial geometry of electronic Bloch states gives birth to topological insulators that are robust against sufficiently weak randomness, inevitably present in any quantum material. However, increasing disorder triggers a quantum phase transition into a featureless normal insulator. As the underlying quantum critical point is approached from the topological side, small scattered droplets of normal insulators start to develop in the system and their coherent nucleation causes ultimate condensation of a trivial insulation. Unless disorder is too strong, the normal insulator accommodates disjoint tiny topological puddles. Furthermore, in the close vicinity of such a transition the emergent islands of topological and trivial insulators display spatial fractal structures, a feature that is revealed only by local topological markers. Here we showcase this (possibly) generic phenomenon that should be apposite to dirty topological crystals of any symmetry class in any dimension from the Bott index and local Chern marker for a square lattice-based disordered Chern insulator model.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
6 Pages, 3 Figures (Supplemental Material as ancillary file)